This will improve with more automation and cut-to-fit boxes. For now, every human shipper cannot have access to an unlimited number of box sizes. It's possible

This will improve with more automation and cut-to-fit boxes. For now, every human shipper cannot have access to an unlimited number of box sizes. It's possible to route orders to shipper lanes with the optimal box size stocked, but daily demand and product selection may not allow. I can't comment on every single 'box is 10x the size of the product', but most likely boil down to the largest dimensional box size by order weight. For example, given standard FedEx DIM Factor, it costs the same amount to ship an 8lb order in a 15x5x5 box as a 44x5x5 box. If the shipping lane(s) w/ the optimal size box (15x5x5) are too busy to get the order out, nothing is lost by sending through a less busy lane in a box up to 44x5x5.